SPIP project

General design of the scientific project of the SPIP team

1. Mechanical muscle properties

This axis will focus on the muscle mechanical properties and the underlying neuromuscular mechanisms and musculo-tendon interactions, in the continuation of the work previously carried out in our laboratory (Morel et al., 2015; Samozino et al., 2016; Fouré et al., 2019; Trama et al., 2019). The purpose of this work is to improve sports performance by optimizing training programs (training, recovery, treatment of pathologies, rehabilitation, return to sport, monitoring, medical follow-up) that aim at developing muscle mechanical properties and diminishing the risk of injury. This purpose will be divided into three objectives.

The first objective is to analyse the link between muscle mechanical properties, evaluated with different scales (from the global level considering the limbs in their entirety to the local level focusing on certain tissue characteristics) and sports performance, in particular explosive performances (e.g. sprints and jumps). For example, one of the projects will determine the optimal force-velocity profile in sprinting using a biomechanical model and will validate this model experimentally with the ultimate goal of individualizing training. Another project will focus on the identification (by imaging and elastography) of the local mechanical properties of the musculotendinous system to determine the efficiency of force production and transmission in the context of performance (Fouré et al., 2013). Another project will focus on the link between the mechanical properties of the musculo-tendon system and performance in football during the repetition of maximum efforts.

The second objective is to better understand the alterations or adaptations of these muscle mechanical properties and its mechanisms with exercise-related constraints such as fatigue, intense mechanical constraints (e.g. vibrations, impacts), eccentric contraction, aging or injuries. For example, a project will focus on changes in the mechanical properties of the musculo-tendon system during an exercise inducing tissue damage (Foure et al., 2019). In addition, the effect of the exercise conditions (force and speed of contraction, soft-tissue vibration) and the effect of muscular profile of the athlete on fatigue-induced reduction in force producing capacities and on intermuscular coordination will be studied.

The third objective focuses on the problem of performance in sprint and hamstring muscle injury with the aim of concomitantly analyze the determinants of performance and injuries in order to identify risk factors related to muscle mechanical properties (Morin et al., 2015). This will be complemented by a more global (epidemiological and interventional) approach of injury prevention in track-and-field events (Edouard et al., 2015a, 2015b, 2016)). One of the projects aims to better characterize the alteration of the hamstrings mechanical properties, either locally at tissue level or at the macroscopic level in terms of sprinting force production, before or after injury (to the hamstrings or anterior cruciate ligament) in order to better prevent the risk of injury and optimize return to sport. These three objectives will be achieved by a combination of biomechanical, neuromuscular, epidemiological and data management approaches, and by favoring explosive sports models (athletics/sprint, football, rugby).

2. Joint mobility and stability

This research axis will be centered around mobility and joint stability applied to two joint models: shoulder and knee. Regarding the shoulder, our work has brought additional knowledge on the motion of healthy shoulder in an ecological situation and on key factors of adaptation of the shoulder to exercise, identified in laboratory conditions (Rogowski et al., 2016; Gillet et al., 2017; Blache et al., 2018). The overall goal was to design and validate programs to improve training and primary prevention (Goulet & Rogowski, 2016). A first scientific objective is then to understand the mechanisms of instability of the glenohumeral joint and to validate physical performance tests evaluating the functional capacities of the shoulder in order to develop training programs. A second objective is to refine the kinematic and musculoskeletal models of the shoulder in order to make them specific to the population studied.

Regarding the knee, the scientific literature reported that the reconstruction of the anterior cruciate ligament alone is not enough to fully recover the knee function (Webster & Hewett, 2019). For example, our studies have evidenced persistent post-surgery interarticular coordination deficits (Pairot de Fontenay et al., 2014; Blache et al., 2017). In addition, we have shown that reconstruction of the anterolateral knee structures appears to be a promising approach to increase knee stability after ACL injury (Neri et al., 2018, 2019; Blache et al., 2019)). The scientific objective in the next few years is to determine the predictive criteria for the success of a knee ligamentoplasty (reconstruction of the anterior cruciate ligament, multi-ligament, anterolateral structures) (Rambaud et al., 2017). Two levels of evaluation will be taken into account: the surgical act (ie in-vitro evaluation and simulation) and the analysis of the factors that favors return to sport (rehabilitation, re-athletics, and resumption of sport).

These objectives will be achieved by a mechanistic (understanding of the mechanisms and factors causing the injury by an analytical and functional biomechanical assessment and modeling) and an interventional (implementing measures/strategies to improve performance while limiting the risk of injury and improving the return to sport while limiting the risk of recurrence) approach.

3. Locomotion in mountain environment

Due to the geographic location of one of its sites on the Alpine arc (Chambéry), the LIBM had always worked on topics related to the mountain environment, either in the development of equipment (skis, shoes, compression garments) or in the field of performance in mountain-related sports (alpine and nordic skiing, trail running) (Falda-Buscaiot et al., 2017; Giandolini et al., 2017; Balducci et al., 2017; Alhammoud et al., 2019). More recently, climbing has enriched these research activities with the support of national and international federations. A common thread in this research area is the specificity of locomotion in the mountain environment. This is first related to the elevation factor, either positive (uphill sections in trail running, nordic ski, climbing with maximum verticality) or negative (alpine skiing, downhill sections in trail running). This feature significantly changes the biomechanics and energetics of human locomotion. The particularity of the support/ground, and therefore of the interface with the practitioner, is also a source of scientific interest. Trail runners run on unstable and variable (stony, grassy) terrains. Skiers are in contact with an unstable and variable snowy ground, requiring an adapted mode of locomotion. Consequently, the equipment needs to be adapted, to both prevent injuries and improve athletes’ performance.

Precisely evaluating the locomotion in mountain environment, sometimes in extreme conditions (altitude, cold) is very challenging. Thanks to their experience and their collaborations with national and international federations (climbing, alpine skiing, nordic skiing, ski mountaineering) and industry, researchers from the SPIP team aim to address these scientific and technological challenges. This research axis thus aims to better understand the determinants of locomotion in mountain situations to improve performance and prevent injury.